The whole thing began as an experiment. A grad-school project. Was it possible to catalog the entire Web, with its daunting tangle of links? Yes. Hence, Google.

Google today owns at least a dozen massive server farms, each of which contains thousands of linked computers. This infrastructure, which allows every Google user to search billions of Web pages in hundredths of a second, constitutes the largest reservoir of pure computational power on the planet. Page and Brin will continue to use this reservoir as the platform for developing Google's core search functions, as well as its other commercial services, new and old.

But they will also use it to conduct experiments. Page recently spoke a little about one of the experiments currently being conducted at Google. "My prediction is that when A. I. happens, it's going to [require] a lot of computation," he told the American Association for the Advancement of Science last year. "Not so much clever algorithms. Just a lot of computation. If you look at [a human's] programming, your DNA, it's about 600 megabytes, compressed. So it's smaller than any modern operating system. Smaller than Linux or Windows. . . . So your program algorithms probably aren't that complicated." Then he added, "We have some people at Google who are trying to build artificial intelligence, and to do it at a large scale. . . . I don't think it's that far off."

Page and Brin, businessmen, have built a hugely profitable company that's coming increasingly close to accomplishing its mission of organizing and making accessible the accumulated output of the human mind.

Page and Brin, scientists, may soon spark the emergence of a mind that is not human at all.